Titanium dioxide pigments



Patented June 13, 1939 v UNITED STATES PATENT OFFICE 2,161,975 TITANIUM DIOXIDE PIGMENTS No Drawing.

Application January 8, 1937, Serial No. 119,625. In Germany January 25, 1936 9 Claims.

This invention-relates to titanium pigments. It has particular reference to titanium dioxide possessing improved properties in respect to lightand' weather-resistance, as well as other desirable properties.

An object of this invention is the preparation of titanium dioxide pigments possessing improved pigment properties, particularly improved resistance to weathering. Another object of this inlo vention is the preparation of titanium dioxide possessing increased resistance against the action of light. Still another object of this invention is the preparation of titanium dioxide pigments which are substantially free, as compared with ordinary titanium pigments, from a tendency to cause the bleaching of organic dyestuffs.

In accordance with the present invention the process of manufacture of titanium dioxide pigments comprises the step of treating the same with a solution of a basic aluminium salt.

Among the basic aluminium salts adapted for use in the process of the present invention highly basic aluminium salts such as for example the highly basic chloride, bromide, iodide, formiate D and acetate may be employed with particular advantage, such highly basic aluminium salts being obtainable for example according to the processes described in the paper by A. Miiller, Journal fiir anorganische Chemie, volume 57, 1908, page 311 00 et seq., and in the paper by M. Adolf and W Pauli in the Kolloid-Journal", volume 29, (1921), part 6, page 282 et seq., furthermore in Gmeiin, Handbuch der anorganischen Chemie 8th edition, delivery 1, part B, page 205-206, as well as in Bulletin de la Socit Chimique de France (3), 13, 1895, seite 56, by E. Schlumberger.

A typical method of preparing basic aluminium chloride is described in Gmelin l. 0., according to which upon dissolution of freshly precipitated 40 Al(0H)3 in A101: solutions or upon addition to the AlCls solutions of NazCOa, solutions of basic aluminum chloride are obtained, the composition of which, depending upon the added amount of hydroxide, may be expressed by the for- 5 mulae A12Cl5OH, A12C14(OH)2, AhCh(OH)a, and

AhCh(0H)4. In general it is sufllcient to employ these sal in the form of a very dilute solution.v However, the concentration of the solution should be so 50 adjusted that even on prolonged; standing no turbidity caused by separated aluminium hydroxides occurs. In general the concentration of the solution may vary between a content of about 0.2% and about 50% of basic aluminium salt.

55 Whenemploying distilled water or water sub stantially freed by other means from hardness the desired effect is attained even with a 0.1% solution of basic aluminium chloride in the soltened water.

The temperature during the reaction may vary 5 according to the conditions. I have obtained good results at a temperature above 0 C. and especially at .a temperature from about 0 C. to about 100 C., more particularly with temperatures ranging from about 15 C. to about C. 10

The calcined and ground titanium dioxide is stirred in a suitable manner in the aluminium salt solution for about 1 to about 4 hours. The mixture is filtered, the residue thoroughly washed with water and finally dried. Instead of the cal- 15 cined titanium dioxide also the uncalcined hydrous titanium oxide is applicable for the process of this invention. Furthermore previously prepared composite pigmentof titanium dioxide with for example barium sulfate or calcium sulfate 2 may be employed for this purpose. Titanium dioxide pigment thus obtained may be used as such or it may be mixed in the known manner with an extender, such as for example barium sulfate, calcium sulfate. calcium carbonate, zinc oxide g5 and the like.

Prior to my invention it has been suggested to suspend titanium oxygen compounds in a solution of. aluminium sulfate and to precipitate aluminium from such mixtures by the addition of an alkaline compound such as carbonate, sodium hydroxide, ammonium hydroxide and the like. My invention, as will be readily perceived, is distinguished irom such proceduranot only by fact the I do not use an alkaline neutralising .or precipitating agent, but also by the fact that I use a basic aluminium salt as distinguishedfrom the normal-aluminium salts suggested by the-prior art. i

The following examples will illustrate the in- 40 vention; the parts being by weight: v I

Example 1 v y 10 parts by weight of titanium dioxide are stirred for 3 hours at roomtemperature with 80 parts by weight of a clear, 0.1% solution of a highly basic aluminium chloride containing approximately one equivalent of chlorine per 2 atoms of aluminium, filtered, thoroughly washed and dried at 150 C.

Ezample 2 10 parts by weiiht of titanium dioxide are stirred for 3 hours t room temperature with arts by weight of a clear, 1% solution of ahighly 2 basic aluminium nitrate, filtered, thoroughly washed and dried at 150 C.

Example 3 parts by weight of titanium dioxide are stirred for 4 hours at 25 C. with 80 parts by weight of a clear, 5% solution of a highly basic aluminium iormiate, filtered, thoroughly washed and dried at 150 C.

Example 4 100 parts by weight of titanium dioxide are stirred with 500 parts of water. This mixture is added with suchan amount of basic aluminium acetate which corresponds to 0.7 part by weight of AlzOs. Then the mixture is heated to 70 C. and stirred-for 1 hour. The pigment is filter oil, washed and dried at 150 C.-

Example 5,

100 parts by weight of hydrous titanium oxide are stirredior 3 hours at room temperature with 500 parts by weight of a clear, 0.1% solution oi a highly basic aluminium chloride containing approximately one equivalent of chlorine per 2 atoms of aluminium; Alter filtering andwashingthepigmentiscalcinedintheususl manner. 1

' Example 6 100 parts by weight oi a composite pigment of 50 parts by weight of titanium dioxide and 50 parts byweig'ht oi! barium suli'ate are stirred for 3 hours at room temperature with 80 parts by weight of a clear, 0.1% solution of a highly basic aluminium chloride containing approximately one equivalent of chlorine per 2 atoms oi aluminium, filtered, thoroughly washed and dried at 150' C. p

I claim:

1. In the process for the improvement 01 titanium dioxide for use as a pigment, the step which comprises stirring .titanium dioxide with a solution of a basicsaluminium salt.

2. In the process !or the improvement oi. titaniumdioxide for use as apigment, the step which comprises stirring titanium dioxide with a solutionsoi' a highly basic aluminium, chloride.

3. In the process for the improvement. of titanium dioxide for use as a pigment. the step which comprises stirring titanium dioxide with a solution of a highly basic aluminium chlorde at a temperature 01 about to about C.

4. In the process for the improvement of titanium dioxide for use as a pigment, the step which comprises stirring 10 parts by weight of titanium dioxide for 3 hours at room temperature with 80 parts by weight of a 0.1% solution 01' a highly basic aluminium chloride containing approximately one equivalent of chlorine per 2 atoms of aluminium.

5. In the process for the improvement of. titanium oxide for use as a titanium pigment, the step which comprises stirring hydrous titanium oxide with a solution of a basic aluminium salt.

6. In the process for the improvement of titanium oxide for use as a titanium pigment, the

a step which comprisesstirrin'g 100 parts by weight of hydrous titanium oxide for 3 hours at room temperature with 509 parts by weight of a 0.1% solution of a highly basic aluminium chloride containing approximately one equivalent of chlorine per 2 atoms of aluminium.

"I. In the process for the improvement of a composite titanium dioxide pigment, the step which comprises stirring 10 parts by weight of a composite pigment consisting of 50 parts by weight of titanium dioxide and 50 parts by weight 01' barium sulfate for 3 hours at room temperature with 80 parts by weight oi a 0.1% solution oi a highly basic aluminium chloride containing approximately one equivalent oi chlorine per 2 atoms of aluminium.

8. In the process for the improvement of titanium oxides for use as a pigment; the step which comprises stirring a 0 pound of the group consisting oi! titanium dioxi e and hydrous titanium oxide with a solution of a basic aluminum salt.

9. In the process for the improvement of titanium oxides for use as a pigment, the step which comprises stirring a compound ,0! the group consisting oi titanium dioxide and hydrous titanium oxide with a solution 01. a highly basic aluminum chloride.

KARL WALTER 

